The Association Between Active Transportation and Serum Total 25-Hydroxyvitamin D Levels Among US Childbearing-Aged Women.

Background: Serum total 25-hydroxyvitamin D (25[OH]D) and physical activity (PA) both play important roles in maternal-fetal health. However, a high prevalence of vitamin D and PA insufficiency has been observed in women of childbearing age. Active transportation may increase overall PA levels and potentially boost serum 25(OH)D levels.

Methods: Data from the National Health and Nutrition Examination Survey between 2007 and 2014 were used. A total of 5601 women aged 18-49 years were included. Transportation PA (TPA) was quantified as metabolic equivalents of task and serum 25(OH)D levels was measured. Multivariable logistic regression models adjusted for potential confounders were conducted.

Results: The corresponding adjusted odds ratios associated with vitamin D insufficiency (<50 nmol/L) were 1.09 (95% confidence interval, 0.87-1.37) for 1 to 499 MET minutes per week of TPA, 0.69 (0.52-0.91) for 500 to 1000 MET minutes per week of TPA, and 0.95 (0.72-1.26) for >1000 MET minutes per week of TPA, respectively, compared with no TPA. Using vitamin D deficiency (<30 nmol/L) as the outcome led to similar results. The association between TPA and serum 25(OH)D levels was more robust in high sedentary time.

Conclusions: A moderate level of TPA is related to lower odds of suboptimal vitamin D status among women of childbearing age.